Advances in wireless communication technology have given rise to a number of wireless applications such as pagers, cellular phones, and mobile computing and networking applications. One of the applications, namely mobile computing and networking, allows a mobile device capable of connecting wirelessly to a network to freely move while remaining wirelessly connected to the network. As the mobile device moves between different networks and sub networks (referred to herein as a sub-net), the connection to a first network or sub-net is dropped, as needed, and a connection to a target network or sub-net is established (also termed a handoff). Such a handoff is made possible through an extension of the Internet Protocol (IP) referred to as Mobile IP. In general, Mobile IP creates the perception that the mobile device is always attached to the same network or subnet even as it is moving around. Specifically, Mobile IP allows the mobile device to retain the same network or IP address regardless of the particular network or sub-net to which the mobile device is actually connected. Thus, a remote application can send data packets to the mobile device at the same IP address no matter how many handoffs (i.e., changes in network or subnet connections) may have occurred.
Although Mobile IP allows the mobile device to freely move between different networks and subnets while appearing to maintain the same network connection, the transition is not always a seamless one. For example, when a handoff occurs in the middle of an ongoing data transfer session, some data packets may be sent to a first care-of address before registration of the target care-of address can be completed. As a result, these data packets may become lost, thereby disrupting the flow of data packets to the mobile device. Depending on the duration of the disruption, the data transfer session may be greatly affected. For example, where the network is particularly slow or congested, a large number of data packets may be lost during the handoff, possibly causing an application running on the mobile device to terminate or otherwise fail.
To allow a mobile device to move between different networks and subnets while appearing to maintain the same network connection, a number of techniques are known. One is the use of local link-layer triggers to enhance link-layer messaging. Another is to use a protocol design that considers address auto configuration. Yet another is to use tunneling between a first access node and a second access node while not taking into account address auto configuration. Yet another is to consider link-layer events on a same machine to trigger network-layer events. Further yet is to pre-configure a Care-of-address (CoA) only at a target access node, use tunnels between the target and first access nodes, and duplicate packets by the Home Agent such as to send a packet to each access node (first and target). Yet another is to address fast re-authentication exclusively without tackling address auto configuration. Each of these known techniques has drawbacks, such as one may tackle address auto configuration but will generate large amounts of traffic during each handoff. Another may not generate large amounts of traffic but will not tackle address auto configuration. In any case, each known technique has shortcomings.
Hence, there exists a need for facilitating handoffs for a mobile entity in a wireless communication network while addressing the shortcomings of the prior art.
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